Eerie Howl

If your opponent's Bench isn't full, look at his or her hand. If your opponent has any Baby Pokémon or Basic Pokémon there, choose 1 of them and put it on his or her Bench. Then, switch it with the Defending Pokémon.

Dark Fire

If there are any Darkness Energy cards attached to Dark Houndoom, discard 1 of them and this attack does 30 damage plus 20 more damage (plus 10 more damage for the Darkness Energy you discarded). If there aren't any, this attack does 30 damage.

The flame it breathes is actually a volatile poison it produces internally that ignites when exposed to air.